Science Objectives for Everyone
The Binary Colloidal Alloy Test 6: Phase Separation (BCAT-6-Phase Separation) experiment studies how gas and liquid separate and join together in space. Colloidal liquids, which have tiny particles suspended throughout, are used to study how the two different phases interact. This research gives fundamental insight into the nature of supercritical fluids--fluids having both liquid and gas properties. This information could be used to develop colloidal materials that last longer.

Science Results for EveryoneInformation Pending

The following content was provided by Matthew Lynch, Ph.D., David A. Weitz, Ph.D., and is maintained in a database by the ISS Program Science Office.

Experiment Details

OpNom

Principal Investigator(s)

Matthew Lynch, Ph.D., Procter and Gamble, Cincinnati, OH, United States

David A. Weitz, Ph.D., Harvard University, Cambridge, MA, United States

Taking a series of pictures of a sample that has been mixed in microgravity as it ages over a period of weeks on the International Space Station (ISS) allows scientists to observe sample aging as it happen much more slowly and evenly throughout the samples. New models are needed for creating better product formulations and stabilizers. Presently, stabilizers are expensive and take up product volume.

If scientists can acquire a better understanding of what is happening when gravity is not causing the heavy components to sink to the bottom and the light components to float to the top, this should enable them to create products that are not only better, but likely less expensive to produce. This is what Binary Colloidal Alloy Test-6: Phase Separation (BCAT-6-Phase Separation) aims to achieve.

Procter and Gamble (P&G) is working with NASA to fly samples that will enable them to create better product formulations and stabilizers to extend product shelf life.

Description

When water boils in a pot, liquid and gas water coexist. If this pot of water is sealed, as the temperature and pressure rise, a point will be reached where liquid and gas are no longer distinct phases and above this point you no longer have a liquid or gas, but a supercritical fluid. A supercritical fluid has properties of both liquids and gases; it has the ability to transport dissolved materials and thermal energy (like liquids) and it flows easily (like gases). These combined qualities are used for things like extracting biomolecules from plants for pharmaceutical research, for decaffeinating coffee beans, and it is being looked at by JPL as a propellant for future rocket engines. These BCAT samples model supercritical fluids, and this model is used throughout industry. This experiment is making measurements that cannot be made on Earth and BCAT-3 microgravity experiment has shown that the present model that is used to predict the location of when a supercritical fluid is formed in these model systems is at best incomplete.

The Binary Colloidal Alloy Test-6, Phase Separation (BCAT-6, Phase Separation) experiments examine conditions that result in colloidal crystallization, melting, self-organization, and phase separation of colloidal systems. The evolution toward equilibrium through time is captured on the International Space Station (ISS) or with the accurate measurement of time frames correlated to the pictures taken by a new kind of automated camera.

There are three principle objectives associated with the phase separation studies in BCAT-6, Phase Separation. The first objective is to measure phase separation rates in microgravity in order to develop the underlying theory for predicting product shelf life. The second is to understand how to control the colloidal forces between particles to determine the physics underlying the phase separation process that forces the placement of additives in products to extend their shelf life. It is for this reason, among others, that finding the critical point is so important. The critical point is the point at which gas transitions into a liquid or supercritical fluid. A supercritical fluid has the properties of both a gas and a liquid. The final objective is to understand the fundamental properties of colloid-polymer mixtures to further improve the commercial utilization of these systems. The fundamental fluid physics research could provide the understanding needed to enable the development of better, less expensive, longer shelf-life household products, foods, and medicines. Stabilizers in these products are expensive, take up volume, and are needed to extend the life of products.

Life-support devices in a spacecraft, such as water recycling systems, may benefit from phase separation research. The experiments could also help research on supercritical fluids for rocket fuel in future spacecraft.

Earth Applications

Without the influence of gravity, materials scientists can better see and understand what causes colloidal materials to clump together, separate, and break down. The experiment also studies whether additives can keep colloidal products from deteriorating. Manufacturers are working with NASA to study materials and additives that could extend product shelf life.

The BCAT-6 consists of a set of ten small samples of colloidal particles. The BCAT-6 samples are each contained within a small case the size of a school textbook. The experiment requires a crew member to set up the experiment using a handrail/seat track configuration, ISS Laptop and the Kodak 760 or Nikon D2Sx camera to take digital photographs of the samples at close range. The pictures are down-linked to investigators on the ground for analysis.

The current plan for this experiment is to conduct it over a 7 or 14-day session, each of which can be run incrementally and require about 7 hours of crew time; a third session to mix and photograph all 10 samples (about 4.6 hours of crew time) and then a fourth session at six months to photograph all ten samples which is slotted to take about four hours of crew time. As such, new information will undoubtedly be learned, and the nature of the experiments conducted will evolve to take advantage of this new information.

Session 2: Set up hardware, homogenize samples 3, 4 and 5 one at a time then automatically photograph each sample (using EarthKAM software on laptop) every hour for 14 days each. Perform Crystal Check and Photography procedures on 6-10 if crystals not found/photographed in Session 1. If necessary, tear down after operations are complete but keeping setup intact is preferred to save crew time. .

Session 3: Homogenize and photograph samples 1-10 (using EarthKAM software on laptop) and stow sample module for six months. The experiment is torn down after operations are complete. .

Session 4: At six months after homogenization, manually photograph samples 1 through 10. Re-stow sample module and tear down after operations are complete.

NASA Image: ISS016E027863 - Astronaut Dan Tani photographing the BCAT-3 Sample Module using his own design for a ceiling mount in Node 2 of the International Space Station. Great high contrast pictures of difficult-to-capture images resulted from using this setup (February 2008).+ View Larger Image